The ability of some animals to navigate through detection of the Earth magnetic field is widely accepted today. The reception mechanism is most likely optimal around Earth magnetic field strength, cannot distinguish magnetic North and South, and involves light reception. Lack of a clearly identifiable magnetic compass organ suggests that the magnetic sense is based on a biochemical process integrated with an existing sensory organ, most likely the eye.

Research efforts in magnetoreception are intense, yet little progress has been made in making a solid case for the physical mechanism underlying magnetoreception. The lecture makes the plea that researchers focus on chemical reality and biological purpose as can be found likely, but not definitely, in the activation and deactivation processes of the blue light receptor cryptochrome, the most widely accepted candidate for the biochemical realization of magnetoreception. Questions to be answered through experiment and theory are: What are the elementary reaction steps? How are they linked to activation and deactivation of cryptochrome? Can these steps be magnetic sensitive in principle, given the physical reality of the protein-cofactor system involved? Can a magnetic field dependence be predicted and measured? How is cryptochrome linked to neural sensory processing? Can this link explain magnetoreception? Answers to some of these questions could enrich the study of physical principles of quantum biology and will be discussed in the lecture.